Specifications
Intel
®
Quark Core—System Register Organization
Intel
®
Quark SoC X1000 Core
Developer’s Manual October 2013
56 Order Number: 329679-001US
Table 14. Condition Code Interpretation after FPREM and FPREM1 Instructions
Condition Code
Interpretation after FPREM and FPREM1
C2 C3 C1 C0
1 XXX
Incomplete Reduction:
further interaction required for complete reduction
Q1 Q0 Q2 Q MOD8
Complete Reduction:
C0, C3, and C1 contain the three
least-significant bits of the quotient
000 0
010 1
0100 2
110 3
001 4
011 5
101 6
111 7
Table 15. Floating-Point Condition Code Interpretation
Instruction C0 (S) C3 (Z) C1 (A) C2 (C)
FPREM, FPREM1
Three least significant bits of quotient (See Table 14.)
Reduction
0 = complete
Q2 Q0 Q1 or O/U# 1 = incomplete
FCOM, FCOMP, FCOMPP, FTST,
FUCOM, FUCOMP, FUCOMPP,
FICOM, FICOMP
Result of comparison (see Table 16)Zero or O/U#
Operand is not
comparable
FXAM Operand class (see Table 17) Sign or O/U# Operand class
FCHS, FABS, FXCH, FINCTOP,
FDECTOP, Constant loads,
FXTRACT, FLD, FILD, FBLD, FSTP
(ext real)
UNDEFINED Zero or O/U# UNDEFINED
FIST, FBSTP, FRNDINT, FST, FSTP,
FADD, FMUL, FDIV, FDIVR, FSUB,
FSUBR, FSCALE, FSQRT, FPATAN,
F2XM1, FYL2X, FYL2XP1
UNDEFINED Roundup or O/U# UNDEFINED
FPTAN, FSIN, FCOS, FSINCOS UNDEFINED
Roundup or
O/U#, if C2 = 1
Reduction
0 = complete
1 = incomplete
FLDENV, FRSTOR Each bit loaded from memory
FINIT Clears these bits
FLDCW, FSTENV, FSTCW, FSTSW,
FCLEX, FSAVE
UNDEFINED
Notes:
1. When both IE and SF bits of status word are set, indicating a stack exception, this bit distinguishes
between stack overflow (C1 = 1) and underflow (C1 = 0).
2. Reduction: If FPREM or FPREM1 produces a remainder that is less than the modulus, reduction is complete.
When reduction is incomplete, the value at the top of the stack is a partial remainder, which can be used as
input to further reduction. For FPTAN, FSIN, FCOS, and FSINCOS, the reduction bit is set if the operand at
the top of the stack is too large. In this case, the original operand remains at the top of the stack.
3. Roundup: When the PE bit of the status word is set, this bit indicates whether the last rounding in the
instruction was upward.
4. UNDEFINED: Do not rely on finding any specific value in these bits. See Section 4.8, “Reserved Bits and
Software Compatibility” on page 63.